U.S. Pat. No. 7,081,722 discloses a method and a circuit for driving LEDs in multiphase. A string of LEDs divided into groups connected to each other in series is provided. Each group is coupled to ground through separate conductive paths. A phase switch is provided in each conductive path. By increasing the input voltage, the string of LEDs are caused to turn on, group by group, in a sequence downstream the string.
In the field of LED lighting, a need exists to further enhance lighting functionality and to create specific spatially distributed lighting.